Chapter 6:
Project Time Management
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Learning Objectives
1.
2.
3.
4.
5.
6.
7.
Understand the importance of project schedules and good project time
management.
Define activities as the basis for developing project schedules.
Describe how project managers use network diagrams and
dependencies to assist in activity sequencing.
Understand the relationship between estimating resources and project
schedules.
Explain how various tools and techniques help project managers
perform activity duration estimating.
Use a Gantt chart for planning and tracking schedule information, find
the Critical-Path for a project, and describe how the Program
Evaluation and Review Technique (PERT) affect schedule
development.
Controlling and managing changes to the project schedule.
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1 Importance of Project Schedules
 Managers often cite delivering projects on time as one of
their biggest challenges.
 Fifty percent of IT projects were challenged in the 2003
CHAOS study, and their average time overrun increased
to 82 percent from a low of 63 percent in 2000.*
 Schedule issues are the main reason for conflicts on
projects, especially during the second half of projects.
 Time has the least amount of flexibility; it passes no
matter what happens on a project.
*The Standish Group, “Latest Standish Group CHAOS Report Shows Project Success
Rates Have Improved by 50%,” (www.standishgroup.com) (March 25, 2003).
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Figure 6-1. Conflict Intensity Over
the Life of a Project
0.40
Conflict Intensity
0.35
0.30
Schedules
0.25
Average
Total Conflict
0.20
Priorities
Manpower
Technical opinions
Procedures
0.15
Cost
Personality conflicts
0.10
0.05
0.00
Project
Formation
Early Phases
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Middle Phases
End Phases
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Individual Work Styles and Cultural
Differences Cause Schedule Conflicts
 One dimension of the Myers-Briggs Type Indicator
focuses on people’s attitudes toward structure and
deadline. (Wk8 lecture)
 Some people prefer to follow schedules and meet
deadlines while others do not.
 Different cultures and even entire countries have
different attitudes about schedules.
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Media Snapshot
In contrast to the 2008 Beijing Olympic, planning and scheduling
was very different for the 2004 Olympic held in Athens, Greece.
Many articles were written before the opening ceremonies
predicting that the facilities would not be ready in time…Many
people were pleasantly surprised by the amazing opening
ceremonies, beautiful new buildings, and state-of-the-art security
and transportation systems in Athens.
The Greeks even made fun of critics by having construction
workers pretend to still be working as the ceremonies began.
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Project Time Management Processes
 Activity definition: Identifying the specific activities that the
project team members and stakeholders must perform to
produce the project deliverables.
 Activity sequencing: Identifying and documenting the
relationships between project activities.
 Activity resource estimating: Estimating how many resources
a project team should use to perform project activities.
 Activity duration estimating: Estimating the number of work
periods that are needed to complete individual activities.
 Schedule development: Analyzing activity sequences, activity
resource estimates, and activity duration estimates to create the
project schedule.
 Schedule control: Controlling and managing changes to the
project schedule.
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2 Activity Definition
 An activity or task is an element of work normally found
on the WBS that has an expected duration, a cost, and
resource requirements.
 Project schedules grow out of the basic documents that
initiate a project.
 The project charter includes start and end dates and budget
information.
 The scope statement and WBS help define what will be done.
 Activity definition involves developing a more detailed
WBS and supporting explanations to understand all the
work to be done, so you can develop realistic cost and
duration estimates.
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Activity Lists and Attributes
 An activity list is a tabulation of activities to be included
on a project schedule. The list should include:
 The activity name
 An activity identifier or number
 A brief description of the activity
 Activity attributes provide more information about each
activity, such as predecessors, successors, logical
relationships, leads and lags, resource requirements,
constraints, imposed dates, and assumptions related to the
activity.
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Milestones
 A milestone is a significant event that normally has no
duration.
 It often takes several activities and a lot of work to
complete a milestone.
 Milestones are useful tools for setting schedule goals
and monitoring progress.
 Examples include completion and customer sign-off on
key documents and completion of specific products.
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Activity Sequencing
 Involves reviewing activities and determining
dependencies.
 A dependency or relationship relates to the
sequencing of project activities or tasks.
 You must determine dependencies in order to use
critical path analysis.
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Three Types of Dependencies
 Mandatory dependencies: Inherent in the nature of
the work being performed on a project; sometimes
referred to as hard logic.
 Discretionary dependencies: Defined by the project
team; sometimes referred to as soft logic and should be
used with care because they may limit later scheduling
options.
 External dependencies: Involve relationships between
project and non-project activities.
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3 Network Diagrams
 Network diagrams are the preferred technique for
showing activity sequencing.
 A network diagram is a schematic display of the
logical relationships among, or sequencing of, project
activities.
 Two main formats are the arrow and precedence
diagramming methods.
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Figure 6-2. Sample Activity-on-Arrow (AOA)
Network Diagram for Project X
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Arrow Diagramming Method (ADM)
 Also called activity-on-arrow (AOA) network diagram.
 Activities are represented by arrows.
 Nodes or circles are the starting and ending points of
activities.
 Can only show finish-to-start dependencies.
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Precedence Diagramming Method (PDM)
 Activities are represented by boxes.
 Arrows show relationships between activities.
 More popular than ADM method and used by project
management software.
 Better at showing different types of dependencies.
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Figure 6-3. Task Dependency Types
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Figure 6-4. Sample PDM Network
Diagram
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Three-Point Estimates
 Instead of providing activity estimates as a discrete
number, such as four weeks, it’s often helpful to create
a three-point estimate:
 An estimate that includes an optimistic, most likely, and
pessimistic estimate, such as three weeks for the
optimistic, four weeks for the most likely, and five
weeks for the pessimistic estimate.
 Three-point estimates are needed for PERT estimates
and Monte Carlo simulations.
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4 Schedule Development
 Uses results of the other time management processes
to determine the start and end dates of the project.
 Ultimate goal is to create a realistic project schedule
that provides a basis for monitoring project progress
for the time dimension of the project.
 Important tools and techniques include Gantt charts,
critical path analysis, and PERT analysis.
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5 Gantt Charts
 Gantt charts provide a standard format for
displaying project schedule information by listing
project activities and their corresponding start and
finish dates in a calendar format.
 Symbols include:
 Black diamonds: Milestones
 Thick black bars: Summary tasks
 Lighter horizontal bars: Durations of tasks
 Arrows: Dependencies between tasks
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Figure 6-5. Gantt Chart for Project X
Note: In Project 2003 darker bars are red to represent critical tasks.
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Gantt Chart for Software Launch Project
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Adding Milestones to Gantt Charts
 Many people like to focus on meeting milestones,
especially for large projects.
 Milestones emphasize important events or
accomplishments in projects.
 You typically create milestone by entering tasks that
have a zero duration, or you can mark any task as a
milestone.
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Figure 6-7. Sample Tracking Gantt Chart
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Critical Path Method (CPM)
 CPM is a network diagramming technique used to
predict total project duration.
 A critical path for a project is the series of activities that
determines the earliest time by which the project can be
completed.
 The critical path is the longest path through the network
diagram and has the least amount of slack or float.
 Slack or float is the amount of time an activity can be
delayed without delaying a succeeding activity or the
project finish date.
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Calculating the Critical Path
 Develop a good network diagram.
 Add the duration estimates for all activities on each
path through the network diagram.
 The longest path is the critical path.
 If one or more of the activities on the critical path takes
longer than planned, the whole project schedule will
slip unless the project manager takes corrective action.
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Figure 6-8. Determining the Critical
Path for Project X
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More on the Critical Path
 A project team at Apple computer put a stuffed gorilla on
top of the cubicle of the person who was currently
managing a critical task.
 The critical path does not necessarily contain all the
critical activities; it only accounts for time.
 Remember the example in which growing grass was on
the critical path for Disney’s Animal Kingdom.
 There can be more than one critical path if the lengths of
two or more paths are the same.
 The critical path can change as the project progresses.
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Using Critical Path Analysis to Make
Schedule Trade-offs
 Free slack or free float is the amount of time an
activity can be delayed without delaying the early start
of any immediately following activities.
 Total slack or total float is the amount of time an
activity can be delayed from its early start without
delaying the planned project finish date.
 A forward pass through the network diagram
determines the early start and finish dates.
 A backward pass determines the late start and finish
dates.
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Figure 6-9. Calculating Early and
Late Start and Finish Dates
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Using the Critical Path to Shorten a
Project Schedule
 Three main techniques for shortening schedules:
 Shortening the duration of critical activities or tasks by
adding more resources or changing their scope.
 Crashing activities by obtaining the greatest amount of
schedule compression for the least incremental cost.
 Fast tracking activities by doing them in parallel or
overlapping them.
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Importance of Updating Critical
Path Data
 It is important to update project schedule information
to meet time goals for a project.
 The critical path may change as you enter actual start
and finish dates.
 If you know the project completion date will slip,
negotiate with the project sponsor.
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Program Evaluation and Review
Technique (PERT)
 PERT is a network analysis technique used to estimate
project duration when there is a high degree of
uncertainty about the individual activity duration
estimates.
 PERT uses probabilistic time estimates:
 Duration estimates based on using optimistic, most
likely, and pessimistic estimates of activity durations, or
a three-point estimate.
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PERT Formula and Example
 PERT weighted average =
optimistic time + 4X most likely time + pessimistic time
6
 Example:
PERT weighted average =
8 workdays + 4 X 10 workdays + 24 workdays = 12 days
6
where:
optimistic time= 8 days
most likely time = 10 days
pessimistic time = 24 days
Therefore, you’d use 12 days on the network diagram instead of 10 when
using PERT for the above example.
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7 Schedule Control
 Perform reality checks on schedules.
 Allow for contingencies.
 Don’t plan for everyone to work at 100 percent
capacity all the time.
 Hold progress meetings with stakeholders and be clear
and honest in communicating schedule issues.
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Schedule Control
 Goals are to know the status of the schedule, influence
factors that cause schedule changes, determine that the
schedule has changed, and manage changes when they
occur.
 Tools and techniques include:
 Progress reports.
 A schedule change control system.
 Project management software, including schedule comparison
charts, such as the tracking Gantt chart.
 Variance analysis, such as analyzing float or slack.
 Performance management, such as earned value (see Chapter 7).
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